U.S. patent number 6,856,275 [Application Number 10/033,080] was granted by the patent office on 2005-02-15 for semiconductor article harmonic identification.
This patent grant is currently assigned to Raytheon Company. Invention is credited to Jay P. Charters, Gerald L. Ehlers.
United States Patent |
6,856,275 |
Ehlers , et al. |
February 15, 2005 |
Semiconductor article harmonic identification
Abstract
An harmonic intermodulation article identification system
comprises a scanning dipole antenna response to an RF
intermodulation harmonic product radiated from RF diodes carried by
or embedded in a substrate. The product signature is applied to a
spectrum analyzer that outputs a signature identification to a
comparator. In response to receiving a signature identification,
the comparator scans previously stored signature identifications
for a match. A match indicates the received product identification
from the analyzer defined a specific substrate such as a document
or product tag. A match by the comparator outputs a signal to a
display that indicates the identification of a substrate carrying
RF diodes generating the compared product identification.
Inventors: |
Ehlers; Gerald L. (Linden,
VA), Charters; Jay P. (Fairfax, VA) |
Assignee: |
Raytheon Company (Waltham,
MA)
|
Family
ID: |
21868445 |
Appl.
No.: |
10/033,080 |
Filed: |
December 26, 2001 |
Current U.S.
Class: |
342/42;
340/10.42; 342/44 |
Current CPC
Class: |
G06K
19/067 (20130101); G06K 7/10009 (20130101); G06K
7/086 (20130101); G08B 13/2422 (20130101) |
Current International
Class: |
G06K
19/067 (20060101); G06K 7/10 (20060101); G08B
13/24 (20060101); G06K 7/08 (20060101); G01S
013/74 () |
Field of
Search: |
;342/42,44,50,51,192-193
;340/10.42,10.1-10.4,10.41 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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41 17 157 |
|
Mar 1993 |
|
DE |
|
1 604 220 |
|
Dec 1981 |
|
GB |
|
Other References
PCT Report for PCT/US 02/40933, 8 pages, Jul. 4, 2003..
|
Primary Examiner: Tarcza; Thomas H.
Assistant Examiner: Alsomiri; Isam
Attorney, Agent or Firm: Baker Botts L.L.P.
Claims
What is claimed is:
1. An harmonic article identification system, comprising: a first
signal generator operating to generate an RF signal at a first
frequency; a second signal generator operating to generate an RF
signal at a second frequency; two or more RF diodes carried by an
article and responsive to the first and second frequencies to
generate an harmonic signal; an antenna receiving the harmonic
signal and, in response to receiving the harmonic signal,
generating an analyzer signal; a signal analyzer coupled to the
antenna and responsive to the analyzer signal to identify the
article; wherein the analyzer signal from the receiving antenna to
the signal analyzer comprises a subtraction of the first frequency
signal from twice the second frequency signal.
2. The harmonic article identification system as in claim 1 wherein
the two or more RF diodes comprise a signature identification of
the article.
3. The harmonic article identification system as in claim 1 wherein
the at least two or more RF diodes respond to RF signals in a
frequency range from about 24.0 GHz to about 24.1 GHz.
4. The harmonic article identification system as in claim 1 wherein
the antenna comprises a dipole having a wavelength determined by
either the first frequency or the second frequency.
5. An harmonic article identification system, comprising: a first
signal generator operating to generate an RF signal at a first
frequency; a second signal generator operating to generate an RF
signal at a second frequency; two or more RF diodes carried by an
article and responsive to the first and second frequencies to
generate an harmonic signal; an antenna receiving the harmonic
signal and, in response to receiving the harmonic signal,
generating an analyzer signal; a signal analyzer coupled to the
antenna and responsive to the analyzer signal to identify the
article; wherein the analyzer signal from the receiving antenna to
the signal analyzer varies in accordance with the expression:
6. An harmonic article identification system, comprising: a first
signal generator operating to generate an RF signal at a first
frequency; a second signal generator operating to generate an RF
signal at a second frequency; two or more RF diodes carried by an
article and responsive to the first and second frequencies to
generate an harmonic signal; an antenna receiving the harmonic
signal and, in response to receiving the harmonic signal,
generating an analyzer signal; a signal analyzer coupled to the
antenna and responsive to the analyzer signal to identify the
article; wherein the analyzer signal from the receiving antenna to
the signal analyzer comprises a subtraction of the second frequency
signal from twice the first frequency signal.
7. An harmonic article identification system, comprising: a first
signal generator operating to generate an RF signal at a first
frequency; a second signal generator operating to generate an RF
signal at a second frequency; two or more RF diodes carried by an
article and responsive to the first and second frequencies to
generate an harmonic signal; an antenna receiving the harmonic
signal and, in response to receiving the harmonic signal,
generating an analyzer signal; a signal analyzer coupled to the
antenna and responsive to the analyzer signal to identify the
article; wherein the analyzer signal from the receiving antenna to
the signal analyzer varies in accordance with the expression:
8. An harmonic article identification system, comprising: a first
signal generator outputting an RF signal at a frequency of 24.0
GHZ; a second signal generator outputting an RF signal at a
frequency of 24.1 GHZ; two or more RF diodes carried by an article
and responsive to the 24.0 GHZ frequency and the 24.1 GHZ frequency
to generate an harmonic signal; a dipole antenna receiving the
harmonic signal and, in response to the dipole antenna receiving
the harmonic signal generating an analyzer signal varying in
accordance with the expression:
9. An harmonic article identification system, comprising: a first
signal generator outputting an RF signal at a frequency of 24.0
GHZ; a second signal generator outputting an RF signal at a
frequency of 24.1 GHZ; two or more RF diodes carried by an article
and responsive to the 24.0 GHZ frequency and the 24.1 GHZ frequency
to generate an harmonic signal having a third order intermodulation
product; a dipole antenna receiving or any other tuned antenna
receiving the harmonic signal and, in response to the dipole
antenna receiving the harmonic signal, generating an analyzer
signal varying in accordance with the expression:
10. An harmonic article identification tag, comprising: at least
one RF diode carried by an article and responsive to at least two
RF signals to generate an harmonic signal having a third order
intermodulation product defined by the expression of twice a first
one of the two RF signals less a second one of the two RF signals,
the at least one diode generating harmonic signal characteristics
for RF article identification.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention relates to harmonic article identification,
and more particularly, the invention relates to identification of
an article carrying at least one semiconductor device outputting an
harmonic intermodulation for detection and/or identification.
BACKGROUND OF THE INVENTION
There has been significant effort in the last decade or so to
develop systems for identification of products, either
identification of a particular product from a product signature or
identification of products moving through a defined space. This
effort has resulted in a number of product identification systems
utilizing various technologies to generate and evaluate product
identification signals. One of the most widely used system utilizes
a bar code reader response to a bar coded element carried by a
product or article. As the bar coded element moves through a
scanning field, the response to the scanning field changes and this
change is detected. Such systems are primarily intended only for
identification of products or articles moving through a defined
space, although there is no technological limitation to generate
identification signatures. These systems are restricted in the
areas of utilization due to size and cost restraints.
Other known systems utilize transponder tags carried or otherwise
attached to a product or article. Many of these transponders are
expensive and have a limited range of detection, typically, less
than one meter. There is no known transponder tag detection system
that utilizes harmonic detection for article identification. Again,
transponder tags have found limited use due to the size of the
transponder and the cost of a tag that may be utilized once and
discarded.
In addition to monitoring and tracking articles and products,
identification systems presently in use also find utility in
security applications. This includes document security where size
of the tag has a more significant impact than tags used for article
and product identification for monitoring and tracking. Systems
presently in use for article identification including product
identification and document identification do not provide a
security identification signature or "fingerprint" for a document.
The use of an identification signature enables the recognition of
individual articles or articles in groups identified with a common
identification signature.
Thus, there is a need for an article identification system
utilizing a relatively inexpensive tag or detector element and
having a size that does not burden the article for identification.
Further, there is a need for an article identification system
utilizing a tag that provides an identified signature to separate
identified articles into classes.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an
inexpensive system and method for identifying articles carrying one
or more semiconductor devices that respond to RF frequencies and
radiate harmonic modulation energy. An harmonic article
identification tag in accordance with the present invention
comprises at least one RF diode carried by an article and
responsive to at least two RF frequencies to generate a third
harmonic intermodulation output.
In accordance with one embodiment of the invention, an harmonic
intermodulation article identification system comprises at least
one semiconductor device carried by or attached to an article. The
at least one semiconductor device responds to at least two RF
frequencies to generate an harmonic intermodulation output. This
harmonic intermodulation output RF signal is received by an antenna
having an output connected to a signal analyzer. This signal
analyzer responds to the analyzer signal to identify the article
carrying the at least one semiconductor device.
Also in accordance with the present invention, there is provided an
harmonic article identification system comprising a first signal
generator operating to generate an RF signal at a first frequency
and a second signal generator operating to generate an RF signal at
a second frequency. At least one RF diode carried by an article
responds to the first and second frequencies to generate an
harmonic intermodulation output received by an antenna that
generates an output to a signal analyzer. The antenna is coupled to
a signal analyzer that responds to the analyzer signal to identify
the article carrying the at least one RF diode.
A method for harmonic article identification in accordance with an
embodiment of the present invention comprises generating at least
two RF signals at separate frequencies. In response to the two
separate frequencies, an harmonic intermodulation signal is
generated by at least one RF diode carried by an article and
responsive to the at least two separate frequencies. An analyzer
signal is generated at the output of an antenna receiving the
harmonic intermodulation output and this analyzer signal is
analyzed to generate an article identification signature.
In addition, in accordance with the present invention, there is
provided an identification system for articles carrying at least
one semiconductor device that generates an harmonic intermodulation
output. The identification system comprises a signal analyzer
responsive to the harmonic intermodulation output to generate an
article identification signal applied to a comparator. Also coupled
to the comparator is a signature memory storing the article
identification signatures of at least one article for
identification. The comparator responds to the article
identification signal from the signal analyzer and scans each of
the article identification signatures stored in the signature
memory. The comparator generates a signal to identify an article
carrying at least one semiconductor device from the stored
signatures.
Technical advantages of the present invention include an
inexpensive system and method for identifying articles tagged with
at least one semiconductor device. The system identifies both from
far (one to three meters) and near (less than one centimeter)
environments. A further advantage of the present invention is the
utilization of inexpensive RF diodes and strong RF signals to
detect harmonics at a distance not heretofore possible by use of
near field antenna apertures to scan the article and record an
identification signature to be verified. A further technical
advantage of the present invention is cost reduction and expansion
of opportunities for identification in areas of monitoring,
tracking and security that have heretofore been prohibited due to
the size and cost restraints of tags and responding systems.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is schematic diagram of an identification system utilizing
microwave horn antennas radiating a semiconductor device to
generate a third harmonic intermodulation signal;
FIG. 2 is a block diagram of a signal analysis system responsive to
a third harmonic intermodulation signal to identify a substrate;
and
FIG. 3 is a flow diagram of the process for generating article
identification utilizing two RF signals for radiating RF diodes in
a substrate for identification.
DETAILED DESCRIPTION OF THE INVENTION
Although the invention will be described with reference to
identification of a signature on a document, it should be
understood that this is a preferred embodiment and the invention
finds utility in many applications other than document signature
identification. For example, and not by way of limitation, the
harmonic intermodulation system and method of the present invention
may be utilized for identification of the presence of a document
without specifically identifying individual documents. Further, the
invention finds utility in identification of the signature or
presence of articles other than documents carrying at least one RF
diode that generates a third harmonic intermodulation output. Thus,
the invention finds utility in commercial and government uses for
classified and unclassified documents and other articles.
Referring to FIG. 1, there is illustrated a schematic diagram of a
system for identifying an RF tagged article for signature
recognition of a multiple tagged article. The RF tag system 10 of
FIG. 1 comprises a first frequency generator 12 generating a first
frequency signal applied to a microwave horn antenna 16. A second
frequency generator 14 outputs a second frequency applied to a
microwave horn antenna 18. Typically, the horn antennas are
positioned to radiate an RF diode 20 at right angles to the diode.
In the embodiment of the invention illustrated in FIG. 1, the
signal generator 12 may be a Hewlett-Packard frequency generator
outputting the first frequency F1 at 24.0 GHz @ +4.0 dBm. The
second signal generator 14 may also be a Hewlett Packard frequency
generator outputting the second frequency F2 at 24.1 GHz @ +4.0
dBm. With a first frequency of 24.0 GHz and a second frequency of
24.1 GHz, the RF diode 20 comprises a 24.0 GHz beam lead type. Such
diodes are commercially available and have a size configuration to
enable embedding in a document such that the diode is not visually
apparent.
Although the invention will be described with reference to a first
frequency of 24.0 GHz and a second frequency of 24.1 GHz, it should
be understood that this is a preferred embodiment and other RF
frequencies may be used in implementation of the invention.
Radiating the diode 20 with the first frequency from the signal
generator 12 and the second frequency from the signal generator 14
results in the diode producing a third order intermodulation
product. This harmonic signal is detected by a dipole antenna 22
that outputs an analyzer signal to a spectrum analyzer 24. In one
embodiment of the invention, the dipole antenna 22 comprises a
dipole having a length of one wavelength at the output of either
the signal generator 12 or the signal generator 14. The spectrum
analyzer 24 responds to the analyzer signal to generate a signature
display 26 that identifies the presence of the diode 20 and the
intermodulation output. The spectrum analyzer 24 also outputs a
signature signal for additional processing of the analyzer signal
from the dipole antenna 22.
In operation of the system of FIG. 1, the signal generator 12
outputs a frequency at 24.0 GHz and the signal generator 14 outputs
a 24.1 GHz frequency. These two frequencies are applied to the horn
antennas 16 and 18, respectively, to radiate the RF diode 20
thereby generating a third order intermodulation product detected
by the dipole receiver antenna 22. For the specific frequencies of
24.0 GHz and 24.1 GHz, the third order intermodulation product
would be two RF frequencies at 23.9 GHz and 24.2 GHz. When the
first frequency F1 is 24.0 GHz and the second frequency F2 is 24.1
GHz, then the analyzer signal from the dipole antenna 22 varies in
accordance with the expression 2F1-F2=23.9 GHz or in accordance
with the expression 2F2F1=24.2 GHz. With power levels from the
signal generators 12 and 14 of approximately +4.0 dBm, the spectrum
analyzer 24 responds to third order intermodulation products in the
-100 dBm range.
Referring to FIG. 2, there is illustrated a block diagram of an RF
tagging system 30 for identification of RF diode signatures in a
substrate 32, such as a document or article tag. One or more RF
diodes 34 are embedded in or carried by the substrate 32 in a
selected "x-y" coordinate position. The one or more diodes 34 are
radiated by frequency signals from RF frequency generators, such as
signal generators 12 and 14 of FIG. 1. Radiating the one or more RF
diodes 34 creates a signature intermodulation output that uniquely
identifies the document carried by the diodes. In addition, the x-y
coordinate position of the diodes 34 on the substrate 32 provides
further authentication of the substrate. Thus, the signature of the
radiated RF diodes 34 identifies the substrate, for example, a
document or tag, and the x-y coordinate position of the diodes
authenticates the signature.
Due to the square law characteristic of high frequency RF diodes,
when the diodes 34 are exposed to a radiated RF field from signal
generators 12 and 14, the diodes will both produce and re-radiate
harmonic related RF energy. This re-radiated RF harmonic energy,
for example, a third harmonic intermodulation product, is received
by a scanning dipole antenna 36. As the substrate 32 passes in
proximity to the scanning dipole antenna 36, the antenna identifies
the x-y coordinate position of the diodes 34 and also responds to
the signature identification resulting from the radiation of the
diodes. This diode position information and the signature
identification received by the dipole antenna 36 is applied to a
spectrum analyzer 38. The spectrum analyzer 38 responds to the
applied position information and signature identification to output
a spectrum analyzer signal coupled to a comparator 40. Also coupled
to the comparator 40 is a signature memory 42 that stores signature
identification data for all substrates (documents, tags) to be
identified by the system. The signature identifications stored in
the memory 42 are pre-programmed into the system by applying
signature identification data on a line 44 coupled to the
comparator 40.
When the comparator 40 receives position information and a
signature identification from the spectrum analyzer 38, the data
stored in the signature memory 42 is scanned and when a comparison
results the comparator 40 outputs an identification signal to a
display 46. The display 46 comprises a visual presentation or hard
copy printout identifying the substrate 32 and authenticating the
substrate.
Referring to FIG. 3, there is illustrated a flow diagram of the
process for identifying RF tagged articles. Two RF signals are
generated at an initial process sequence 50. These two RF frequency
signals are applied to microwave horn antennas 16 and 18 to radiate
RF diodes during process sequence 52. The RF diodes carried by or
embedded in a document, tag or other substrate radiate third order
intermodulation products received by a dipole antenna to generate a
product signature at process sequence 54. The product signature is
applied to an inquiry sequence 56 to evaluate if the product
signature is a new signature not previously received. A positive
response to the inquiry sequence 56 directs the product signature
to a memory during a store process sequence 58.
A negative response to the inquiry sequence 56, indicating that the
product signature from the process sequence 54 is not new, advances
the process for article identification to a scanning process
sequence 60. During the scanning process sequence 60, the product
signature from the process sequence 54 is compared with the store
product signatures in the scanning process sequence 60. A positive
comparison between an incoming product signature and one of the
stored product signatures advances the identification process to
generate an article identification during a process sequence
62.
In addition to document identification by product signature, the
process of FIG. 3 also finds utility in identification of the
authenticity of a document. Instead of the document carrying one or
more embedded RF diodes defining a product signature, the document
would carry only one RF diode. The process of FIG. 3 is modified to
remove the process sequences 56, 58 and 60 and the product
signature from the process sequence 54 comprises a signal
identifying the presence of an RF diode in a document. The presence
of the RF diode in the document is an indication of authenticity of
the document as generated in the process sequence 62.
While the invention has been described with reference to the
illustrated preferred embodiment, it is intended to cover such
alternatives, modifications and equivalents as may be included in
the spirit and scope of the invention as defined in the following
claims.
* * * * *